I realized that I want to make it up to my step son since he will be living with us already . How can be a good step mom ?

Be genuine enough yesha , show to him that he is important and let him feel that he belong . A mothers love is the best weapon that would break the wall between you and your step son . Took care of him like his your own and by that everything will fall into a perfect place.

I think the first step is to make him feel welcome and love. I think it's important for a child to feel like he belongs with the family he's in :)